ML15195A392

Response to NRC Request for Additional Information, Dated May 22, 2015 Regarding License Renewal Application, Environmental Review, SW-07 on Water Resources

ML15195A392
Person / Time
Site:	LaSalle
Issue date:	07/02/2015
From:	Exelon Generation Co
To:	Office of Nuclear Reactor Regulation
Shared Package
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References
RS-15-179
Download: ML15195A392 (1)

Text

1 LaSalle Environmental Audit Response to Request for Additional Information Index #:

035 RAI #: SW-07 Category: Water Resources Statement of Question:

As referenced in ER Section 2.2.3 relative to the screen backwash systems for the lake screen house and river screen house, respectively, clarify and briefly describe whether the backwash systems actuate automatically at some set frequency and/or via differential pressure preset, or if operator intervention is required to activate the backwash systems.

Response

The River Screen House (RSH) traveling screens can be placed in Auto or Manual (Slow or Fast speed) mode. They are left in Auto unless unusually high debris intake requires cleaning by hand. In Auto, the screens activate in Slow speed when differential water level across the screens reaches 4 in. If differential level continues to rise to 6 in., the screens shift into Fast speed. If differential level exceeds 16 in. for at least 15 seconds, the associated makeup pumps will trip to prevent cavitation damage. When differential level is reduced to 3 in., a timer continues to rotate the screens for one full revolution, and then brings them to a stop. During periods of high debris intake, the screens may be left in Manual mode in either Slow or Fast speed as needed to prevent high differential level.

The Circulating Water (CW) traveling screens located at the Lake Screen House can be placed in Auto or Manual mode, but they are usually left in Auto. In this mode, when differential level is between 0 and 6 in., a timer initiates a 3-minute wash cycle every 12 to 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br />. If differential level increases to between 6 and 10 in., the screens start washing continuously at their Slow speed. If differential level continues to increase to between 10 and 12 in., the screens shift into Fast speed. During fish runs or other periods of high debris intake, the screens may be left in Manual mode in either Slow or Fast speed as needed to prevent high differential level.

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